Botulinum Toxin Injections to the Obliquus Capitis Inferioris Muscle for Dynamic Cervical Dystonia Improves Subjective Patient Outcomes

Abstract

The obliquus capitis inferioris (OCI) muscle is a significant driver of cervical dystonia with torticaput movements and a no–no head tremor. Limited data are available on the efficacy of OCI injections on patient outcomes. Our study aims to determine whether the botulinum toxin injection into OCI improves subjective patient quality of life in those with dystonic head tremors. A retrospective chart review was performed for 25 patients receiving injections into the OCI for a dystonic head tremor at the London Movement Disorders Clinic between January 2020 and January 2022. Toronto Western Spasmodic Torticollis Scale-2 (TWSTRS-2) subscale scores for disability and pain, TWSTRS-PSYCH scores, and the global impression of severity were extracted. The average TWSTRS-2 disability subscale change was −2.8 points (p < 0.003). The average TWSTRS-2 pain subscale change was −4.6 points (p < 0.003). The average TWSTRS-PSYCH score prior to injection was 5.6. After injection, the average score was 3.7 (p < 0.004). The patient self-reported average global impression of severity before injection was 7.0; after this, it was 4.2 (p < 0.0003). The OCI injection showed significant improvement in retrospective patient self-reported outcomes; it should be considered early in the treatment plan for cervical dystonia with a no–no head tremor.